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perf(parser): reuse export kind classification (#28424)

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Reuse the classified export kind to avoid duplicate lookahead for type-only exports; remove the obsolete classifier.

Local arm64: type-export fixtures take 4–9% less parse time; ordinary corpus is flat (−0.36%, −0.24% with tokens). Largest slower control: +1.5%.

Validated parser and Node suites, unchanged conformance and allocations, and 63,568 differential comparisons.

AI assistance: Codex.
This commit is contained in:
Boshen committed 2026-10-29 15:09:00 +00:00
1 parent 03d5b3a99e
commit 1b5a171d28
1 file changed
+20 -55
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crates/oxc_parser/src/js/module.rs
+20 -55
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@@ -531,20 +531,26 @@ impl<'a, C: Config> ParserImpl<'a, C> {
Kind::Default => ModuleDeclaration::ExportDefaultDeclaration(
self.parse_export_default_declaration(start, decorators),
),
Kind::Star => {
ModuleDeclaration::ExportAllDeclaration(self.parse_export_all_declaration(start))
}
Kind::LCurly => self.parse_export_named_specifiers(start),
Kind::Star => ModuleDeclaration::ExportAllDeclaration(
self.parse_export_all_declaration(start, ImportOrExportKind::Value),
),
Kind::LCurly => self.parse_export_named_specifiers(start, ImportOrExportKind::Value),
Kind::Type if self.is_ts => {
let next_kind = self.lexer.peek_token().kind();
match next_kind {
// `export type { ...`
Kind::LCurly => self.parse_export_named_specifiers(start),
Kind::LCurly => {
self.bump_any(); // bump `type`
self.parse_export_named_specifiers(start, ImportOrExportKind::Type)
}
// `export type * as ...`
Kind::Star => ModuleDeclaration::ExportAllDeclaration(
self.parse_export_all_declaration(start),
),
Kind::Star => {
self.bump_any(); // bump `type`
ModuleDeclaration::ExportAllDeclaration(
self.parse_export_all_declaration(start, ImportOrExportKind::Type),
)
}
_ => ModuleDeclaration::ExportDeclaration(
self.parse_exported_declaration(start, decorators),
),
@@ -581,8 +587,11 @@ impl<'a, C: Config> ParserImpl<'a, C> {
// ExportSpecifier :
// ModuleExportName
// ModuleExportName as ModuleExportName
fn parse_export_named_specifiers(&mut self, start: u32) -> ModuleDeclaration<'a> {
let export_kind = self.parse_import_or_export_kind();
fn parse_export_named_specifiers(
&mut self,
start: u32,
export_kind: ImportOrExportKind,
) -> ModuleDeclaration<'a> {
let opening_span = self.cur_token().span();
self.expect(Kind::LCurly);
let (mut specifiers, _) = self.context_remove(self.ctx, |p| {
@@ -824,8 +833,8 @@ impl<'a, C: Config> ParserImpl<'a, C> {
fn parse_export_all_declaration(
&mut self,
start: u32,
export_kind: ImportOrExportKind,
) -> ArenaBox<'a, ExportAllDeclaration<'a>> {
let export_kind = self.parse_import_or_export_kind();
self.bump_any(); // bump `star`
let exported = self.eat(Kind::As).then(|| self.parse_module_export_name());
self.expect(Kind::From);
@@ -1028,50 +1037,6 @@ impl<'a, C: Config> ParserImpl<'a, C> {
}
}
fn parse_import_or_export_kind(&mut self) -> ImportOrExportKind {
if !self.is_ts {
return ImportOrExportKind::Value;
}
// OK
// import type { bar } from 'foo';
// import type * as React from 'react';
// import type ident from 'foo';
// export type { bar } from 'foo';
// NO
// import type from 'foo';
// OK
// import type from from 'foo';
if !self.at(Kind::Type) {
return ImportOrExportKind::Value;
}
let next_kind = self.lexer.peek_token().kind();
if matches!(next_kind, Kind::LCurly | Kind::Star) {
self.bump_any();
return ImportOrExportKind::Type;
}
if !(next_kind == Kind::Ident) && !next_kind.is_contextual_keyword() {
return ImportOrExportKind::Value;
}
if next_kind != Kind::From
|| self.lookahead(|p| {
p.bump_any();
p.bump_any();
p.at(Kind::From)
})
{
self.bump_any();
return ImportOrExportKind::Type;
}
ImportOrExportKind::Value
}
fn parse_export_specifier(
&mut self,
parent_export_kind: ImportOrExportKind,